Screw-propeller blade.



No. 683,&08. Pateted Oct. eo.

s. N. smm.

SGBEW PBOFELLER BLADE.

(Applicat filed Jun 19 1901) No Model.)

Hima??? W W. %i W W w W W W OM UNITED STATES PATENT rrron SOMMERS N. SMITH, OF PHILADELPHIA, -PENNSYLVANIA.

SCREW-PROPELLER BLADE.

SPECIFICATION forming part of Letters Patent No. 683,&08, dated October 1, 1901.

Application filed .Tune 19, 1901.

To all whom, it mer/y concrn:

Be it known that I, SOMMERS N. SMITH, a citizen of the United States, residing in Philadelphia, Pennsylvania, have invented certain 'Improvements in screw-Propeller Blades, ot'

which the following is a specification.

The object of ny iuvention is to so construct a propeller-blade that the resistance to the passage of the same through the water will be reduced to a minimum, an object which I attain in the manner hereinafter set forth, reference being had to the accompanying drawings, in which-- Figure 1 is a face View of a propeller-blade constructcd in accordance with my invention. Fig. 2 is a transverse section of the same; and Figs. 3, 4, and 5, are respectively sections on the lines a a, Z b, and c c, Fi 1.

In the drawings I' have shown a hub l with single blade 2 5 but of course it will be understood that the hub may have any desired number of blades, and where the blades are cast separately from the hub each blade will have a boss or head for being bolted to the hub.

The blade is, as shown in Figs. 2 to 5, of symmetrical cross-section-that is to say, it is the same on each side of its center line instead of having the impellingface of the blade in the form of a helical surface, with the material arranged on'one side of the same, as in the usual design or Construction of propeller-blades.

Besides having the symmetrical distribution of metal mentioned above my improved ropeller-blade has the greatest thickness of blade-section between the helical center of the blade and the leading edge of the same, the exact location of said greatest thickness of blade-section being fixed. by the number of revolutons, the immersion of the propeller, the under-water shape of the hull, and other conditions usually taken into account in the designing of the blades of propellers.

In the blade shown in the drawings the section of greatest thickness is on the line w, which is about one-third of the helical length of the blade from the leading edge of the same.

Serial No, 65,149. (No model.)

By making the blade of symmetrical crosssection and by disposing the point of greatest thickness between the helical center of the blade and the leading edge of the same I materially reduce the resistance of the water to the passage of the blade through it, since the water is uniformly divided on each side of the blade and the latter passes through the water with the least possible disturbance of the stream-lines, which are symmetrical in cleavage at the leading edge of the blade uniform while passing the blade, and close in after passing the blade with the least possible readjustment. By this means I overcome that loss of power which in an ordinary propeller results from the distorted stream-linos due to the unsymmetrical blade-section, the results as compared with the operation of an ordinary propeller being lessened vibration, an increased number of revolutions or increased pitch of screw, or sometimes both, without increase of horse-power, or a lessening of horse-power without lessening either the number of revolutions or pitch of screw, and sometimes even with an increase of one or both of these screw factors, the ultimate result being higher speed for the same consumption of fuel or a lessened consumption of fuel for the same speed.

Having thus'described myinvention, I wish it to be understood that Ido not claim,broadly, a propeller-blade having a symmetrical crosssection--that is to say, a section which is alike on each side of the center line; but I claim as my invention and desire to secure by Letters Patent- A propellerblade of symmetrical crosssection and having the greatest thickness of blade-section between the helical center of the blade and the leading edge of the same.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

SOMMERS N. SM ITH.

Witnesses:

FRANK E. BEOHTOLD7 J os. H. KLEIN. 

